Apoptosis usually refers to programmed cell death of body cells occurring via the regulation of intracellular genes and products thereof during a development process or under the action of some factors. Apoptosis commonly exists in the biosphere under both a physiological state and a pathological state. It plays important roles in embryo development and morphogenesis, stability of normal cells in tissues, defense and immune reaction of body, cell damage caused by diseases or poisoning, ageing, generation and development of tumors, and is one of the hottest spots in biomedical research.
Some researches show that the occurrence of many serious diseases relates to the over apoptosis of cells, for example, the reduction of CD4+ T cells during the development of ADIS; the cell death mediated by cytotoxic T cell during transplant rejection reaction; the apoptosis of myocardial cells and nerve cells of ischemia and reperfusion injury; nervous system degradation diseases (such as Alzheimer disease, Parkinson's disease, etc.); apoptosis caused by exposure to ionizing radiation in many tissues.
Some evidence has indicated that cardiomyocyte apoptosis closely associates with the occurrence, development and prognosis of many heart diseases. It is found in the research about cardiomyocyte apoptosis that the infarct of cardiac muscle is not equivalent to myocardial necrosis, and apoptosis is one of mechanisms of myocardial infarction, and is the main manner of myocardial death of early infarction and myocardial death caused by ischemia/reperfusion, and the apoptosis of cardiomyocytes in large amounts at this time aggravates myocardial damage. In 1989, Nepomniashchikh et al found in the observation of ultrastructure of hunger myocardial atrophy that the synthesis of cardiomyocytes' structural protein decreased, and the cell number decreased but was not accompanied with a proportional decrease of cell nucleus, and thus preliminarily proposed that hunger myocardial atrophy was caused by apoptosis. In 1994, Gottlieb and Kawano et al obtained direct evidence of cardiomyocyte apoptosis by using electron microscope in combination with DNA gel electrophoresis, in which the former disclosed reperfusion injury induced rabbit cardiomyocyte apoptosis, and the latter confirmed that myocarditis patients had concomitant cardiomyocyte apoptosis. Tanaka et al also confirmed the existence of apoptosis of cardiomyocytes in suckling mice. With the progress of methodology and research of apoptosis, pathological functions of cardiomyocyte apoptosis have been found in many heart diseases. Some researches indicate the heart injury in spontaneously hypertensive rat (SHR) is relevant to apoptosis; the conversion from cardiac pachynsis to heart failure in advanced stage is caused by cardiomyocyte apoptosis; acute myocardial infarction also induces apoptosis in early stage of infarction and reperfusion injury, except necrosis; cardiomyocyte apoptosis is also found in transplanted heart and right ventricular maldevelopment myocardial diseases, and anoxia also induces cardiomyocyte apoptosis.
Apoptosis has recoverability in some extents, and the apoptosis in myocardial infarction and ischemia/reperfusion has its own features and regular patterns, so that the features may be used for prevention and reduction of apoptosis and may provide enlightenment for clinical prophylaxis of ischemia/reperfusion injury; during the process of reperfusion, the apoptosis occurring in the contraction band region (around infarction site) is induced by some precipitating factors, so that the inhibition factors of apoptosis such as drugs may be used for preventing apoptosis and treating corresponding diseases caused by apoptosis.
However, there are few kinds and numbers of drugs so far that can be clinically used for anti-apoptosis and protecting cells, and their selectivity and targeting property are not satisfactory, and therefore it is of great significance to continuously develop new, safe and effective drugs for anti-apoptosis and protecting cells, and especially drugs with a novel mechanism of action.